This document discusses Felix HTTP, a modular web application framework. It provides an overview of the current state, available extensions, and a new specification. The new specification standardizes the whiteboard pattern and adds support for asynchronous servlets, filters, listeners, custom error pages, WebSockets, SPDY, and the Servlet 3.0 API. Future work includes finalizing the new specification and improving support for technologies like SPDY and WebSockets.

1. Felix HTTP
Paving the road to the future
and Jan Willem Janssen Marcel Offermans
SSID: Felix
Password: felixdemo
Browse to: http://10.61.0.161:8080/

2. Jan Willem
Janssen
Software architect at Luminis Technologies
Currently working on PulseOn and Amdatu
Committer and PMC member at Apache Felix and Apache ACE

3. Marcel
Offermans
Director at Luminis Technologies, Fellow at Luminis
Currently working on Amdatu
Apache Member, Committer and PMC member at Apache ACE and
Apache Felix

4. Agenda
Modular Web Applications
Current State
Available Extensions
The New Specification
New extensions
Future Work
Wrap Up

5. Modular Web
Applications

6. Modular
Architectures
High Cohesion, Low Coupling
Separation of Concerns
Maintainable Code
Reusable, Composable

7. Deployments
Compose modules into different deployments
Low bandwidth by just sending changed modules
Fast deployments by being able to update running applications

8. Current State

9. Explicit
RegistrationpublicinterfaceHttpService{
voidregisterServlet(Stringalias,Servletservlet,
DictionaryinitParams,HttpContexthttpContext);
voidregisterResources(Stringalias,Stringname,
HttpContexthttpContext);
voidunregister(Stringalias);
HttpContextcreateDefaultHttpContext();
}

10. Servlets
httpService.registerServlet("/hello",newHttpServlet(){
@Override
publicvoiddoGet(HttpServletRequestreq,HttpServletResponseresp){
resp.setContentType("text/plain");
resp.getWriter().write("HelloApacheConworld!");
}
},null/*initParams*/,null/*httpContext*/);
invoke the /hello servlet
...

11. ResourceshttpService.registerResources("/site","/resources",null/*httpContext*/);
$catresources/hello
HelloApacheConworld,I'mastaticresource!
request a static resource called hello
...

12. HttpContext
Provides secure access to servlets and resources.
Layer of abstraction for resource loading.
publicinterfaceHttpContext{
booleanhandleSecurity(HttpServletRequestrequest,
HttpServletResponseresponse);
URLgetResource(Stringname);
StringgetMimeType(Stringname);
}

13. Web Application
Specification
Part of the OSGi Enterprise Specification, chapter 128.
Web Application Bundle (WAB) are extended Java EE WAR files.
They have optional JSP support.
Integration with OSGi BundleContextand service registry.

14. Available
Extensions

15. Whiteboard
don't call us, we'll call you!
Register your Servletin the service registry and add a property called
aliascontaining its endpoint.
For more information:
http://www.osgi.org/wiki/uploads/Links/whiteboard.pdf

16. Filters
Just like Servlets, these can be registered whiteboard style
or use explicit registration:
the ExtHttpServiceservice from Felix HTTP
the WebContainerservice from PAX Web

17. Amdatu Web
Resources
of the open source project (Apache Licensed).Part Amdatu.org
X-Web-Resource-Version:1.1
X-Web-Resource:/amdatu-resources;resources
X-Web-Resource-Default-Page:index.html,/doc=javadoc.html
Include-Resource:resources=resources/basic

18. Demo
request a static resource called /amdatu‑resources
...

19. Amdatu Web
REST
Extensive support for based on industry standards.REST endpoints
JAX-RS based annotation support.
Includes support for Jackson mappings.
Self-documenting endpoints with Swagger.

20. Demo@Path("/rest")
@Description("ProvidesademoRESTendpoint")
publicclassDemoRestEndpoint{
privateStringm_response="HelloWorld!";
@GET@Produces(MediaType.TEXT_PLAIN)
@Description("Givesaplaintextresponse")
publicStringgetPlainResponse(){
returnm_response;
}
@POST@Consumes(MediaType.APPLICATION_FORM_URLENCODED)
@Description("Allowsonetosettheresponsetoreturn")
publicvoidsetResponse(
@FormParam("response")@DefaultValue("Defaultresponse")StringnewResponse){
m_response=newResponse;
}
}

21. Self-
documenting
Endpoints
Swagger is a library that creates documentation for endpoints based on
JAX-RS annotations plus some extras.
Go to Swagger documentation

22. The new
specification

23. Whiteboard
No longer an extension
No explicit registration
Specify HttpService to be used

24. Example
Dictionaryprops=newHashtable();
props.put("osgi.http.whiteboard.servlet.pattern","/slidemgr");
props.put("osgi.http.whiteboard.target","(http.service=demo)");
context.registerService(Servlet.class.getName(),newSlideManager(),props);

25. (A)synchronous
Servlets
Servlet 3.0 API
Support wildcard one or more patterns
Process work outside the servlet lifecycle

26. Example code
classWorkerServletextendsHttpServlet{
protectedvoiddoGet(HttpServletRequestreq,HttpServletResponseresp){
finalAsyncContextasyncContext=req.startAsync(req,resp);
asyncContext.start(newDeepThought(asyncContext));
}
}
//
classDeepThoughtimplementsRunnable{
privateAsyncContextm_context=//...
publicvoidrun(){
//...dosomehardwork...
TimeUnit.DAYS.sleep(356L*7500000L);
HttpServletResponseresponse=(HttpServletResponse)asyncContext.getResponse();
response.setStatus(SC_OK);
response.getWriter().printf("42");
asyncContext.complete();
}
}

27. Example registration
Dictionaryprops=newHashtable();
props.put("osgi.http.whiteboard.servlet.pattern","/worker/*");
props.put("osgi.http.whiteboard.servlet.asyncSupported","true");
context.registerService(Servlet.class.getName(),newWorkerServlet(),props);

28. Filters
Full support

29. Example
Dictionaryprops=newHashtable();
props.put("osgi.http.whiteboard.filter.pattern","/*");
props.put("osgi.http.whiteboard.filter.dispatcher",
newString[]{"REQUEST","INCLUDE","FORWARD"});
context.registerService(Filter.class.getName(),newSecurityFilter(),props);

30. Listeners
Full support
All events

31. Example
finalCountDownLatchlatch=newCountDownLatch(1);
ServletContextListenercontextListener=newServletContextListener(){
publicvoidcontextDestroyed(ServletContextEventevent){}
publicvoidcontextInitialized(ServletContextEventevent){
latch.countDown();
}
};
Dictionaryprops=newHashtable();
props.put("osgi.http.whiteboard.context.select","DEFAULT");
context.registerService(ServletContextListener.class.getName(),contextListener,props);
assertTrue("HttpServicenotreadyintime?!",latch.await(5,TimeUnit.SECONDS));
//continuewithyouritest...

32. Custom Error
Pages
By error code
By exception

33. Example
Dictionaryprops=newHashtable();
props.put("osgi.http.whiteboard.servlet.errorPage",
newString[]{"500","java.io.IOException"});
context.registerService(Servlet.class.getName(),newMyErrorHandlingServlet(),props);

34. New extensions

35. WebSockets
“Real-time”
Binary or text-based
Two-way communication
RFC 6455

36. Example
//Client-side
varwsConn=newWebSocket("ws://"+window.location.host+"/servlet",["my-protocol"]);
wsConn.onmessage=function(event){
vardata=event.data;
//dosomethingwithdata
}
//Server-side,registeredat"/servlet"
classMyWebSocketServletextendsWebSocketServlet{
publicWebSocketdoWebSocketConnect(HttpServletRequestrequest,Stringprotocol){
if("my-protocol".equals(protocol)){
returnnewWebSocket.OnTextMessage(){
publicvoidonOpen(Connectionconn){}
publicvoidonClose(intcode,Stringreason){}
publicvoidonMessage(Stringdata){}
};
}
returnnull;
}
}

37. Demo
Multi-user Etch A Sketch

38. SPDY
Let's make the web faster
Session layer on top of SSL
Reduce bandwidth & lower latency
Push multiple resources in a request
Basis of HTTP 2.0

39. Application
Session
Presentation
Transport
How SPDY fits in the OSI layer model.

40. SPDY vs WebSockets
SPDY WebSockets
Goal optimize HTTP 2-way communication
Upgradeability transparent needs works
Secure? ✔ (mandatory) ✔ (if needed)
Two-way? ✔ / ✘ ✔
Multiplexed ✔ ✘
Prioritized ✔ ✘

41. Demo
HTTP vs SPDY

42. Future Work

43. Finalize support for new HttpService specification
Upgrade to Jetty 9
Allow “new style” WebSockets (JSR 356) to be used
Improved support for SPDY

44. Wrap Up

45. New/updated specifications
New features, functionality & improvements
Available extensions
Build modular web applications

46. Questions?

47. Links
felix.apache.org
luminis-technologies.com
bndtools.org
amdatu.org
bitbucket.org/marrs/apachecon2014-felix-http